Carbonate compounds are useful as specialty solvents in fields such as pharmaceutical and agricultural chemistry, and as starting materials and intermediates in preparation of dyes, agricultural chemicals, and pharmaceuticals. Carbonate compounds are also used as electrolyte solvents for non-aqueous batteries containing cathodes made from alkali metals, alkaline earth metals, or compounds comprising these metals, for example lithium ion batteries.
Current lithium ion battery electrolyte solvents typically contain one or more linear carbonates, such as ethyl methyl carbonate, dimethyl carbonate or diethylcarbonate; and a cyclic carbonate, such as ethylene carbonate. However, at battery voltages above 4.4V, these electrolyte solvents can decompose and cause a loss of battery performance. Additionally, there are safety concerns with the use of these electrolyte solvents because of their low boiling point and high flammability.
To overcome the limitations of conventional nonaqueous electrolyte solvents, several new carbonate compounds have been developed. For example, U.S. Pat. No. 5,659,062 describes carbonate compounds given by the general formula R1CH2O—CO—OCH2R2, wherein R1 represents a hydrogen atom, an alkyl group, or an alkyl group substituted with one or more halogen atoms, and R2 represents an alkyl group having no hydrogen atom at the •-position thereof or an alkyl group substituted with one or more halogen atoms and having no hydrogen atom at the •-position thereof, with the proviso that R1 is not identical to R2. Additionally, WO 08/79670 describes fluorinated cyclic and acyclic carbonate solvents such as various fluorine-substituted 1,3-dioxolane-2-one compounds and fluorine-substituted 1,3-dioxane-2-one compounds.
A need still remains, however, for electrolyte solvents that are highly stable to oxidation and have a high boiling point.